4. Top-down design means that we start at the highest level of the hierarchy, or that the entire project is considered to exist in a closed dark box with inputs and outputs.
8. In the digital clock project, when it is 11:59:59, AND gate 1 detects that the tens of hours is 1 and the edge trigger clock moves the display to 12:00:00.
10. In the frequency counter, a pulse shaper block is needed to ensure that the unknown signal, whose frequency is to be measured, will be compatible with the clock input for the counter block.